Automobile frame and body designs have taken into account the need for absorbing the impact of frontal collisions. To this end, U.S. Pat. No. 3,869,017 provides an example of an impact absorbing system for a motor vehicle containing both a plastically deformable energy absorbing frame section and break-away engine mounts which fracture in the event of a catastrophic collision and permit the engine to separate from the frame. Once the engine is separated, according to this design, the frame sections need support only the inertia load of the vehicle body. However, the design does not prevent the engine from invading the passenger compartment, where it can cause injuries to occupants.
In similar fashion, U.S. Pat. Nos. 3,718,304, 3,851,722, 4,073,357, and 4,181,192 disclose energy absorbing chassis members having severable engine mounts which allow the engine blocks to be severed from the frame in the event of a substantial impact or when a critical deceleration rate is reached. However, the releasable mounts disclosed therein do not necessarily work in cooperation with each other, so that in offset frontal impacts the engine may be only incompletely released from the frame. There is no teaching, furthermore, as to how dislocation of the engine block is controlled.
An energy absorbing motor mount assembly is disclosed in U.S. Pat. No. 4,238,104 wherein a pair of mounting elements are attached to arms that extend downward into containment housings with resilient springs for frontward and backward movement. Presumably, energy absorption is provided in fore and aft directions, but the assembly does not provide for, and in fact teaches against, the decoupling of the engine from the mounts in substantial impacts.
U.S. Pat. No. 3,638,748 discloses a chassis-frame structure having upper and lower sets of longitudinal members. A transverse cross-member which connects one of the sets of longitudinal members forces an engine block to be pivoted into the ground. The longitudinal members also flex and buckle into the ground so that the vehicle front end is raised accordingly. The movement of the engine block is substantially limited, such that the moment of inertia of the engine is not sufficiently isolated from the vehicle as a whole.
U.S. Pat. No. 4,238,104 discloses a motor mount assembly in which a mounting element, such as an arm having an enlarged head portion, is mounted for reciprocation in fore and aft directions against biasing springs inside a containment housing. The arm also permits side-to-side motion of the mounted engine. The freedom of motion permitted by this assembly, however, is limited. In a frontal collision of substantial impact the engine block must be sheared from the mounts to substantially disengage its moment of inertia from the vehicle chassis frame.
In view of the foregoing disadvantages, an engine block mount is needed for decoupling the inertial body of the engine from the vehicle frame while controlling its position relative to the frame during substantial impacts.